Common Supplement Shows Concerning Link to Heart Failure

Recent research into a widely used sleep supplement has raised alarms about potential long-term health risks. A large study of adults suffering from insomnia found troubling associations with extended use of melatonin.

Study Findings

The analysis, which is not yet peer-reviewed, examined data from more than 130,000 adults across several countries. Participants who used melatonin for over a year showed a markedly increased likelihood of serious heart conditions.

Long-term melatonin users had an 89% higher risk of heart failure over five years.
They were twice as likely to die from any cause compared to non-users.

"Among more than 130,000 adults across multiple countries, those prescribed melatonin long-term had an 89 percent higher risk of heart failure over five years, and were twice as likely to die from any cause."

While the results highlight potential risks, scientists caution that the findings are preliminary and do not alter current medical guidance. There's no conclusive evidence yet that melatonin directly causes harm.

Context and Next Steps

Melatonin ranks as the fourth most common natural supplement among adults in the United States. Short-term usage of one to two months is generally viewed as safe for non-pregnant, non-breastfeeding individuals. However, researchers emphasize that more investigation is needed into long-term effects as its popularity increases.

"The findings are preliminary and don't change current health recommendations. What the results do suggest is that longer-term uses of melatonin need to be studied further to ensure they are safe."

The study was presented at the American Heart Association's Scientific Sessions.

Author Summary

Preliminary research links prolonged melatonin use to increased heart failure risk, urging scientists to reevaluate its safety for long-term users.

ScienceAlert — 2025-11-07